Optical sensor

ABSTRACT

An optical sensor includes an interaction region configured to comprise an analyte and an illumination source configured to illuminate the interaction region with an optical input signal. The optical sensor further includes an optical coupling structure configured to collect transmitted parts of the optical input signal from the interaction region and an optical neuromorphic network that is directly optically coupled to the optical coupling structure and is configured to receive and process the transmitted parts of the optical input signal in the optical domain. The invention further concerns a related method for analyzing an analyte by an optical sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/428,511 filed Feb. 9, 2017, the complete disclosure of which isexpressly incorporated herein by reference in its entirety for allpurposes.

BACKGROUND

The present invention relates generally to an optical sensor foranalyzing an analyte, in particular for detecting elements such asparticles in liquids or gases, liquids, gases and/or plasma.

The invention also relates to a corresponding method for analyzing ananalyte.

Optical sensors to detect chemical substances and small particles aree.g. used for analyzing gases, contaminants in liquids or biologicalparticles. These sensors are often very bulky and may comprise e.g.large laser systems and mechanical components. Accordingly, they areoften driven by significant power levels and hence not well suited forsmall sensors as desired for example in the field of Internet of Things.

Such optical sensors usually comprise a light source and correspondingoptics to illuminate the sample. Then scattered, transmitted and/orabsorbed light is detected, converted in the electrical domain andelectrically processed for determining the desired information.

Accordingly, there is a need for other optical sensors.

SUMMARY

According to a first aspect, the invention is embodied as an opticalsensor comprising an interaction region configured to comprise ananalyte and an illumination source configured to illuminate theinteraction region with an optical input signal. The optical sensorfurther comprises an optical coupling structure configured to collecttransmitted parts of the optical input signal from the interactionregion and an optical neuromorphic network being directly opticallycoupled to the optical coupling structure and being configured toreceive and process the transmitted parts of the optical input signal inthe optical domain.

Hence, according to embodiments, the optical neuromorphic network canperform at least a part of the processing for the analysis/detection inthe optical domain. This facilitates the design of detection andanalysis systems that may provide advantages in particular in terms ofspeed, accuracy and power consumption. Furthermore, it may facilitatethe design of compact sensor systems.

The term transmitted parts of the optical input signal shall encompassall parts of the optical input signal that can be collected by theoptical coupling structure. This encompasses scattered, reflected and/ordistracted parts of the optical input signal. The transmitted parts ofthe optical input signal shall also include any kind of changes to theoptical input signal that may occur due to any interaction of theoptical input signal with the analyte such as phase changes, frequencychanges, or optical absorption. Furthermore, the transmitted parts ofthe optical input signal may also comprise changes to the optical inputsignal that may occur as a result of an interaction of the analyte withthe interaction region itself, e.g. with the surface of the interactionregion. The latter may also change the optical transmissioncharacteristics of the interaction region.

The term analyte shall be understood in a broad sense to denote any kindof analytes or combinations of analytes that can be analyzed, inparticular detected, by an optical sensor, e.g. particles, molecules,gases, plasma, chemical substances, contaminants in liquids, biologicalparticles, etc.

According to an embodiment, the optical neuromorphic network isconfigured to be trained on performing a classification of the analyte.

The classification may be done according to embodiments with lowlatency. Furthermore, according to such an embodiment, the neuromorphicnetwork may be trained specifically to the respective targetedapplication. As an example, according to one embodiment, theneuromorphic network may be trained to just distinguish two sets ofgases with high precision, while according to another embodiment theneuromorphic network may be trained to distinguish e.g. 10 sets of gaseswith lower precision.

According to an embodiment, the optical neuromorphic network isconfigured to be trained on performing a forecasting of one or moreproperties of the analyte. Such a forecasting/prediction may be e.g. theforecast that a gas concentration will exceed a predetermined thresholdwithin a predetermined amount of time.

According to an embodiment, the optical neuromorphic network is anoptical reservoir system.

According to an embodiment, the optical reservoir system comprises aplurality of optical reservoir nodes and a plurality of opticalreservoir connections between the plurality of optical reservoir nodes.

Such an embodied neuromorphic network operates as a reservoir computingunit in the optical domain.

According to embodiments, systems that operate according to thereservoir computing paradigm have reservoir connections with weightsthat are set at the beginning of a learning operation and that do notchange during the learning operation, while only output connections ofthe reservoir system are trained during the training operation.

Hence according to a further embodiment, the neuromorphic networkcomprises one or more input nodes, one or more output nodes and aplurality of output connections between the optical reservoir nodes andthe one or more output nodes. One or more of the output connectionscomprise weighting elements that can be adjusted during a trainingprocess. According to a preferred embodiment the output nodes, theplurality of output connections and the weighting elements operate alsoin the optical domain. In other words, optical output connections,optical weighting elements and optical output nodes are provided.

According to such an embodiment, only the output connections of thereservoir system are configured to be weighed and trained for a desireddetection target, while the reservoir connections and reservoir nodeshave a fixed state/weight during the training. The training may use asoftware algorithm to perform the training, such as providinginformation about how to adjust the weights of the optical weightingelements. The resulting trained state of the reservoir system is theencoded in the hardware, i.e. in the weighting elements, preferably in anon-volatile way.

According to an embodiment, the optical neuromorphic network comprises aplurality of output layers. Each of the plurality of output layers isconfigurable to be trained on performing a classification according todifferent classification criteria. The classification criteria may bee.g. the particle size and/or the particle concentration of elements tobe detected. The plurality of output layers may be formed by one or morereservoir systems.

According to embodiments, nodes and connections of the optical reservoirsystem and in particular the optical weighting elements may comprisematerials whose optical properties can be modified permanently, butchangeably, such that a change may be long term. This can be achievedthrough stimuli applied to the respective tunable element, in particularthe optical weighting elements, during the training process. It shouldbe noted that generally according to embodiments the reservoir systemmay be trained at any level. Preferably the weighting is performed atthe level of the output connections only, as described above. Thestimuli may be optical, electrical, thermal, mechanical, magnetic, etc.,and may depend on the material of the nodes and/or connections and inparticular of the material of the optical weighting elements that areused to form the network.

According to an embodiment, the optical neuromorphic network comprisesone or more nonlinear optical elements.

The nonlinear optical elements may be e.g. optical amplifiers,detectors, or optical attenuation elements.

According to an embodiment, the optical coupling structure comprises oneor more optical waveguides.

According to an embodiment, the interaction region comprises a circularregion having a circular shape. The circular region is surrounded by atleast one waveguide configured to illuminate the interaction region andby at least one waveguide to collect the transmitted parts of the inputsignal.

Such an embodied interaction region provides a flexible and efficientsolution to provide the optical input signal to the interaction regionand to collect the transmitted parts of the optical input signal thathave interacted with the analyte.

According to an embodiment, the sensor is configured to process aplurality of different wavelength. This further enhances the possibleprocessing parameters of the sensor and may improve the detectioncapabilities.

According to an embodiment, the sensor comprises a plurality ofinteraction regions.

This may further enhance the detection capabilities of the sensor. E.g.each of the interaction regions may be adapted for a specific purpose,e.g. to detect a specific particle or a specific particle size.

According to an embodiment, a first interaction region may be used as areference region, comprising e.g. a liquid with a fixed distribution ofparticles, and a second interaction region may be used as sensingregion, e.g. for sensing an unknown solution

According to an embodiment, the sensor comprises a plurality of opticalreservoir systems.

According to such an embodiment, each of the optical reservoir systemsmay be e.g. trained for a specific purpose, e.g. to detect a specificparticle or a specific particle size.

According to an embodiment, the interaction region comprises amicrofluidic channel. Furthermore, the illumination source is configuredto illuminate at least a part of the microfluidic channel.

The microfluidic channel may be e.g. configured to carry the analyte ina dissolved form in a fluidic medium. The term fluidic medium shallencompass liquids and gases. According to embodiments, thewalls/surrounding materials confining the microfluidic channel maycomprise silicon oxide, silicon nitride, polymers, silicon, III/Vmaterials and/or functional oxides such as BaTiO3.

According to an embodiment, the interaction region comprises a waveguidestructure and a surface or bulk of the waveguide structure is configuredto interact with the analyte. This embodiment may be in particularuseful for the detection of gases.

According to an embodiment, a surface of the interaction region may befunctionalized as to provide specific adsorption sites for molecules tobe detected. If a respective molecule is then present in the interactionregion, it will be adsorbed by the adsorption sites. This in turnchanges the optical behavior/transmission characteristic of thewaveguide and hence the transmission of the optical input signal whichcan be detected by the optical sensor.

According to an embodiment, the sensor is configured to use static lightscattering, dynamic light scattering and/or absorption spectroscopy toanalyze the analyte.

These are well-established methods which can be used to employ efficientand reliable detection/analysis schemes in dependence on the respectivedetection/analysis task.

According to an embodiment, the illumination source is a broadbandillumination source. According to other embodiments, the opticaltransmitter may operate at one or more single wavelengths/emission peaksor may comprise an illumination source whose wavelength can be tuned.According to other embodiments, the illumination source may change thespectrum in time, or be modulated.

According to an embodiment, the sensor is configured such that thetransmitted parts of the optical input signal have a different spectrumthan the optical input signal.

Such an embodied sensor may use e.g. Raman spectroscopy or fluorescence.

According to another aspect of the invention, a method for analyzing ananalyte by an optical sensor is provided. The method comprises steps ofilluminating, by an illumination source, an interaction regioncomprising the analyte with an optical input signal and collecting, byan optical coupling structure, transmitted parts of the optical inputsignal from the interaction region. The method comprises further stepsof forwarding, by the optical coupling structure, the transmitted partsof the optical input signal to an optical neuromorphic network andreceiving and processing the transmitted parts of the optical inputsignal in the optical domain by the optical neuromorphic network.

Embodiments of the invention will be described in more detail below, byway of illustrative and non-limiting examples, with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic block diagram of an optical sensor according toan embodiment of the invention;

FIG. 2 shows a schematic illustration of a top view of an optical sensoraccording to another embodiment of the invention comprising aninteraction region formed by a microfluidic channel;

FIG. 3 shows a schematic illustration of an optical sensor according toanother embodiment of the invention comprising an interaction regionformed by a waveguide;

FIG. 4 shows a schematic illustration of a top view of an optical sensoraccording to another embodiment of the invention comprising a pluralityof interaction regions and a plurality of optical reservoir systems;

FIG. 5 shows a schematic illustration of a side view of an interactionregion according to another embodiment of the invention;

FIG. 6 shows a schematic illustration of an interaction region havingmultiple illumination sources; and

FIG. 7 illustrates method steps of a method for analyzing an analyte byan optical sensor according to embodiments of the invention.

DETAILED DESCRIPTION Definitions

Neuromorphic networks are widely used in pattern recognition andclassification, with many potential applications from fingerprint, iris,and face recognition to target acquisition, etc. The parameters (e.g.,‘synaptic weights’) of the neuromorphic networks can be adaptivelytrained on a set of patterns during a learning process, following whichthe neuromorphic network is able to recognize or classify patterns ofthe same kind.

A key component of a neuromorphic network is the ‘synapse,’ at whichweight information is stored, typically as a continuous-valued variable.

Neuromorphic networks may be used for several types of learning. For theoptical sensor according to embodiments of the invention, a “supervisedlearning approach” may be favorably used. With such a supervisedlearning approach a set of (input, desired output) pairs is provided tothe neuromorphic network, one at a time, and a learning algorithm findsvalues of the “weights” (the adjustable parameters of the neuromorphicnetwork) that minimize a measure of the difference between the actualand the desired outputs over the training set. If the neuromorphicnetwork has been well trained, it will then process a novel (previouslyunseen) input to yield an output that is similar to the desired outputfor that novel input. That is, the neuromorphic network will havelearned certain patterns that relate input to a desired output.Furthermore, it may generalize this learning to novel inputs. Moreparticularly, optical sensors according to embodiments may be trainedwith a plurality of input sets of elements/analytes that shall bedetected/analyzed by the optical sensor. Thereby the sensor learns therespective transmission characteristics of these elements/analytes foroptical input signals illuminating the interaction region.

FIG. 1 shows a schematic block diagram of an optical sensor 100according to an embodiment of the invention.

The optical sensor 100 comprises an interaction region 101 thatcomprises an analyte 102 that shall be detected by the optical sensor100. The analyte 102 may encompass all kind of elements such as e.g.particles, molecules, chemical substances, plasma or gases. The opticalsensor 100 further comprises an illumination source 103 that inoperation illuminates the interaction region 101 with an optical inputsignal 104.

According to embodiments, the illumination source 103 may be a broadbandillumination source. According to embodiments, the illumination sourcemay emit in the mid infrared (IR) range, i.e. in a range between 3 μmand 8 μm. According to other embodiments, the illumination source mayemit in the near IR range, i.e. in a range between 0.7 and 3 μm and/orin the visible range, i.e. in a range between 0.4 μm and 0.7 μm.According to some embodiments, the illumination source may operate at asingle wavelength. According to other embodiments, the wavelength of theillumination source may be tuned.

The illumination source 103 may be a coherent or an incoherent lightsource, e.g. a laser or a LED. The illumination source 103 may be anembedded illumination source fabricated e.g. from III/V or other gainmaterials. According to some embodiments, the illumination source 103may emit the light directly into the interaction region 101. Accordingto other embodiments, the light source 103 may comprise a waveguide oranother optical coupling structure to couple the light generated by theillumination source into the interaction region 101. According to anembodiment, the illumination source 103 may comprise a diffractionpattern to couple the optical input signal 104 into the interactionregion 102. The diffraction pattern may be e.g. a grating coupler. Theoptical input signal 104 may illuminate the interaction region 101 fromany direction that is suitable for the specific geometry of theinteraction region 102. E.g., the illumination source 103 may illuminatethe interaction region 101 from the top, from the side, from the bottom,or any combination thereof.

The optical sensor 100 comprises further an optical coupling structure105 that collects transmitted parts 106 of the optical input signal 104from the interaction region 101 and forwards the transmitted parts 106to an optical neuromorphic network 107. The transmitted parts 106 may beany parts of the optical input signal 104 that can be collected by theoptical coupling structure 105 and hence arrive at the optical couplingstructure 105. The optical input signal may e.g. be scattered,reflected, distracted and/or absorbed by the analyte 102 within theinteraction region 101. The scattered, reflected and/or distracted partsof the optical input signal 104 that are collected by the opticalcoupling structure 105 are denoted as transmitted parts 106 of theoptical input signal 104.

The optical neuromorphic network 107 is directly optically connected tothe optical coupling structure 106 and hence receives the transmittedparts 106 of the optical input signal 104 in the optical domain.Accordingly, the optical neuromorphic network 107 can process thetransmitted parts 106 in the optical domain.

The optical neuromorphic network 107 can be trained on performing aclassification of the analyte 102. The training may be in particularperformed as supervised learning as described above. The opticalneuromorphic network 107 can also be trained on performing a forecast ofone or more properties of the analyte 102, such as a gas concentration.

According to embodiments, the neuromorphic network 107 can be used todetect changes in the transmitted part 106 of the optical input signal.Such an embodied optical sensor 100 is not only sensitive to constantproperties such as particle size and gas concentration of the analyte102, but also to certain temporal patterns and/or changes. E.g., theoutput of the neuromorphic network 107 may indicate if a fluctuation ofthe signal with a certain frequency appears, or if a suddendrop/increase/change in the transmission spectrum appears.

The sensor 100 may be embodied according to various detectionprinciples. According to exemplary embodiments, static light scattering,dynamic light scattering or absorption spectroscopy may be used toanalyze and/or detect the analyte 102.

FIG. 2 shows a schematic illustration of an optical sensor 200 accordingto another embodiment of the invention. The optical sensor 200 comprisesan interaction region 201 that comprises as analyte elements 202 such asparticles or gases that shall be detected by the optical sensor 200. Theinteraction region 201 has a circular shape and is surrounded by aplurality of waveguides. The interaction region 201 comprises amicrofluidic channel 210 that is adapted to transport or carry theelements 202 that shall be detected. The elements 202 may be dissolvedin a fluidic medium of the microfluidic channel 210. The microfluidicmedium may be e.g. water or another microfluidic medium that is suitableto carry the respective elements 202 to be detected. The walls of themicrofluidic channel 210 may comprise or consist of silicon oxide,silicon nitride, polymers, silicon, III/V materials or functional oxidessuch as BaTiO3. The microfluidic channel 210 may have an inlet at a side210 a of the microfluidic channel 210 and an outlet at an opposite side210 b of the microfluidic channel 210.

The microfluidic medium with the elements 202 to be detected may besupplied at the end 210 a of the microfluidic channel 210 and conveyedaway at the end 210 b.

The sensor 200 comprises an illumination source 203. The illuminationsource 203 comprises an optical transmitter 203 a, e.g. a laser, togenerate an optical input signal 204 and a waveguide 203 b to guide theoptical input signal 204 from the optical transmitter 203 a to theinteraction region 201. The illumination source 203 illuminates a partof the microfluidic channel 210, namely the interaction region 201.

The optical sensor 200 comprises an optical coupling structure 205comprising a plurality of waveguides 205 a that are arranged around theinteraction region 201. The waveguides 205 a collect transmitted parts206 of the optical input signal 204 from the interaction region 201 andforward the transmitted parts 206 to an optical neuromorphic network250. According to the embodied optical sensor 200, the opticalneuromorphic network 250 is embodied as an optical reservoir system 250.As in the embodiment of FIG. 1, the transmitted parts 206 may be anyparts of the optical input signal 204 that have been collected andarrived at the optical coupling structure 205. It should be noted thatfor ease of illustration not all waveguides 205 a of FIG. 2 are shownwith a connection to the optical reservoir system 250, but only a subsetof the optical waveguides 205 a. However, according to embodiments allof the waveguides 205 a may be connected to the optical reservoir system250. Furthermore, according to another embodiment some of the waveguides205 a may be connected to other not shown neuromorphic networks oroptical reservoir systems. According to embodiments, one or more of thewaveguides 205 a may be connected to multiple neuromorphic reservoirs.Furthermore, optical amplification structures may be provided in thewaveguides 205 a to enhance the signal, e.g. by a semiconductor opticalamplifier (SOA).

The optical reservoir system 250 is directly optically connected to thewaveguides 205 a and hence receives the transmitted parts 206 of theoptical input signal 204 in the optical domain. Accordingly, the opticalreservoir system 250 can process the transmitted parts 206 in theoptical domain.

The optical reservoir system 250 comprises an optical reservoir 251comprising a plurality of optical reservoir nodes 252 and a plurality ofoptical reservoir connections 253 between the optical reservoir nodes252. The optical reservoir connections 253 are illustrated with solidlines. Some of the optical reservoir nodes 252 are directly connected tothe optical waveguides 205 a and serves as input nodes of the opticalreservoir system 250, e.g. the input nodes denoted with 252*. The inputnodes 252* form an input layer.

The optical reservoir system 250 comprises further a plurality ofoptical output connections 254 between one or more of the opticalreservoir nodes 252 and optical output nodes 256. One or more of theoptical output connections 254 comprise optical weighting elements 255,which can be adjusted during a training process. More particularly, theoptical reservoir system 250 can be trained to perform a classificationof the elements 202 that shall be detected. According to embodiments,the weights of the optical reservoir connections 253 are fixed duringthe training process, i.e. they do not change during the trainingprocess. On the contrary, the weights of the output connections 254 willbe trained and hence may be changed during the training process by theoptical weighting elements 255. The optical output connections 254 areillustrated with dashed lines.

Hence, according to the above described embodiment the training processof the optical reservoir system 250 will only change the weights of anoutput layer formed by the optical output nodes 256 and the outputconnections 254 comprising the optical weighting elements 255. However,the weights of the reservoir connections 253 within the opticalreservoir 251 itself will remain fixed and will not change during thetraining/learning process.

The output nodes 256 deliver an optical output signal, which can beconverted into the electrical domain by suitable converters as known tothe skilled person in the art. The converted output signals may then befurther processed in the electrical domain by suitable hardware orsoftware processing means. The adjustment of the weights of the opticalweighting elements 255 may be also done in software or hardware. Moreparticularly, according to embodiments, a hardware control circuit withadditional control software running on it may receive the output signalsof the output nodes 256 during the training process and may adjust theweights of the optical weighting elements by applying electrical controlsignals to the optical weighting elements 255. The optical weightingelements 255 may be e.g. embodied as optical attenuators or opticalamplifiers. During the training process, certain states of the reservoirsystem may be assessed. In particular, with some learning algorithms,the state of the output connections 254 after the weighting elements 255might be needed. Therefore, parts of the optical signal might be splitto a dedicated detector and fed to the respective learning algorithmduring the training process.

The optical reservoir system 250 comprises some nonlinear signaltransformation elements in the reservoir before the weighting elements255. According to an embodiment, these nonlinear signal transformationelements may be implemented by the optical reservoir nodes 252, or asubset of the optical reservoir nodes 252.

Accordingly, the optical reservoir system 250 may be operated accordingto the reservoir computing paradigm.

While according to this embodiment the conversion from the opticaldomain to the electrical domain is performed at the optical output nodes256, this conversion may be done earlier according to other embodiments.More particularly, according to some embodiments, the conversion to theelectrical domain may be already performed at the reservoir nodes 252that are connected to the output connections 254. According to such anembodiment, the output connections 254 are embodied as electrical outputconnections, the weighting elements 255 are embodied as electricalweighting elements and the output nodes 256 are embodied as electricaloutput nodes. However, it should be noted that also according to such anembodiment the optical reservoir 251 itself with the reservoirconnections 253 and the reservoir nodes 252 are still in the opticaldomain only.

As a result, the output connections 254 are trained output connectionsforming a trained or controlled layer with respect to weighting suchthat the neuromorphic network/reservoir system 250 can compute desiredresults, even with unknown inputs. For example, the neuromorphicnetwork/reservoir system 250 may be configured with an output layer thatis controlled for weighting that when a known input is supplied at theinput nodes/input layer, a known output is generated at the outputnodes/output layer. And, when an unknown input is supplied to thereservoir system 250, the output at the output nodes 256 may be robust,reliable, and accurate.

More particularly, the input layer of the reservoir system 250 receivesthe transmitted parts of the optical input signal corresponding toelements to be identified or classified. This information is thenprocessed by the optical reservoir system 250 and the optical reservoirsystem 250 supplies information identifying or classifying the elementsto the output nodes 256.

As described herein, weights or weighting may be an altering ormodification of a transmission through the output connections 254. Thatis, the transmission of a pulse through the output connections 254 maybe controlled to provide a greater or lesser weight based on thetraining of the network, thus having certain connections be strongerwhile others are weaker. For example, a waveguide can be used where thetransmission is tuned during training. In such an example, the outputinformation may be encoded in the amplitude of an optical signal in thewaveguide. The optical signal can be superimposed with the signal ofother waveguides, and such a system can encode information about a classin different amplitudes.

As another example, weighting may be achieved in a routing changeprocess. For example, one or more Mach-Zehnder interferometers may beused where the phase of the optical mode in one arm of theinterferometer is shifted. A signal of a waveguide can be transferredfrom one waveguide to another waveguide. Such a configuration may enablerouting between different or multiple connections. As a result, thetraining would result in a routing path of input signals to differentoutput waveguides to achieve the desired outcome during the training.

According to embodiments the optical reservoir system may 250 comprise aplurality of output layers that may be formed by different sets of theoutput nodes 256. Each of the plurality of output layers may be trainedon performing a classification according to different classificationcriteria, e.g. particle size and particle concentration.

Those of skill in the art will appreciate that other configurations of aneuromorphic network and an optical reservoir system are possible. Forexample, a reservoir of a neuromorphic network may be configured withvirtual reservoir nodes. Time multiplexing may be used in suchconfigurations.

Accordingly, the optical reservoir system 250 employs reservoircomputing by a reconfigurable reservoir or network. Further, byadjusting the weights of the various connections in the network, thenetwork may be tuned to operate at different stable operation points,and thus may be re-configurable to each of the stable operation points.As described herein, according to embodiments the nodes or neurons ofthe reservoir system may enable hardware tuning of output, input, andreservoir weight. Furthermore, according to embodiments weighting andtraining of the neuromorphic network may be performed at the hardwarelevel. The training may use a software algorithm to perform thetraining, such as providing information about how to adjust the hardwareweights. The resulting trained state of the network is encodednon-volatilely in the hardware (i.e., in the nodes and the connectionsbetween them), rather than being a software weight that is appliedduring the computing process.

In some embodiments, this may be achieved by constructing the reservoirsystem from materials whose optical properties can be modifiedpermanently, but changeably, such that a change in one of the nodesand/or layers may be long term and achieved through stimuli, resultingin a neuromorphic network that is trained at any level and internally,not relaying on any external software and/or algorithms. The stimuli maybe optical, electrical, thermal, mechanical, magnetic, etc., and maydepend on the material of the nodes and/or connections that are used toform the network.

In accordance with an embodiment of the present disclosure, a siliconphotonics chip is configured as an optical sensor comprising an opticalreservoir system. At each or part of the nodes in the reservoir system,a structure, e.g. comprising waveguides, resonators, or interferometershaving variable transmission may be used. The transmission function ofthe resonator may be varied as it is based on materials having a strongelectro-optic coefficient or more generally on materials whose opticalproperties show a dependence on optical or electrical stimuli. Variousnon-limiting examples are materials where the real part refractive indexof the material can be substantially modified upon the application of anelectrical field (e.g., materials with a strong Pockels effect) and/orwhere the imaginary part of the refractive index can be modified by anelectric field/current (e.g., materials with a crystalline phasetransition: VO2, PCM-materials, etc.). Further, in accordance with somenon-limiting embodiments, the change of the optical properties in thematerial might be caused by optical stimuli (e.g., for phasetransitions, photorefractive effect, etc.). Those of skill in the artwill appreciate that other materials may be used, other than silicon.For example, III-V semiconductor materials may be used, withoutdeparting from the scope of the present disclosure.

According to further embodiments, delay lines may be provided within oneor more waveguides 205 a of the coupling structure 205. This may spreadthe transmitted parts 206 of the input signal over time.

According to a further embodiment, the optical reservoir system 250 maycomprise delay lines for spreading out the optical signal that isprocessed for short ranges, e.g. nanoseconds.

According to a further embodiment, the optical reservoir system 250 maycomprise materials such as VO₂ to cause optically induced phasetransitions with long relaxation times to reach longer time scales ofe.g. more than 1 μs.

FIG. 3 shows a schematic illustration of an optical sensor 300 accordingto another embodiment of the invention.

The optical sensor 300 comprises a waveguide structure 310. A part ofthe waveguide structure 310 forms an interaction region 311. In theinteraction region 311 the waveguide structure 310 has a porous surface312 which is indicated in FIG. 3 by the dashed lines. This embodiment isin particular suitable to detect gases, but also suitable fluids may bedetected. More particularly, gases or fluids to be detected may enterthe waveguide structure 310 through the porous surface 312. According tosome embodiments, a detectable gas may then distribute within thewaveguide structure 310 and influence thereby the transmission behaviorof the waveguide structure 310, in particular within the interactionregion 311. According to another embodiment, the surface 312 or bulk 313of the waveguide structure 310 may interact with elements to bedetected. According to embodiments, the surface 312 of the interactionregion may be functionalized and provide specific adsorption sites forspecific molecules to be detected.

The sensor 300 comprises an illumination source 303. The illuminationsource 303 comprises an optical transmitter 303 a to generate an opticalinput signal 304 and a waveguide 303 b to guide the optical input signal304 from the optical transmitter 303 a to the waveguide structure 310.According to other embodiments, the optical transmitter 303 a may alsobe arranged directly within the waveguide structure 310. The opticalinput signal 304 is transmitted from a left end 310 a of the waveguidestructure 310 to a right end 310 b of the waveguide structure 310.During this transmission, the optical input signal 304 interacts withelements to be detected within the interaction region 311 as describedabove. E.g. if a gas has entered the interaction region 311 through theporous surface 312, the optical input signal may be reflected,distracted or scattered by the respective gas. Or, if the surface 312has been functionalized, the gas may interact with the surface 312 andthereby cause a change of the material properties of the surface 312which in return changes the transmission behavior of the waveguidestructure 310 for the optical input signal 304. The transmitted parts306 of the optical input signal are fed via an optical couplingstructure 305 to an optical reservoir system 350 that processes thetransmitted parts 306 in the optical domain. According to thisembodiment, the waveguide structure 305 may only comprise a singlewaveguide that optically connects the waveguide structure 310 with onlyone reservoir node 352 of the optical reservoir system 350. The opticalreservoir system 350 may be embodied in the same or a similar way as theoptical reservoir system 250 as described with reference to FIG. 2.

FIG. 4 shows a schematic illustration of an optical sensor 400 accordingto another embodiment of the invention. The optical sensor 400 comprisesa microfluidic channel 410 that is adapted to transport or carry asanalyte elements 402 that shall be detected. The elements 402 may bedissolved in a fluidic medium of the microfluidic channel 410 asdescribed above with reference to FIG. 2. The optical sensor 400comprises three interaction regions 401 a, 401 b and 401 c. Theinteraction regions 401 a, 401 b and 401 c have all a circular shape andare each surrounded by a plurality of waveguides. The microfluidicchannel 410 has an inlet at a side 410 a of the microfluidic channel 410and an outlet at an opposite side 410 b of the microfluidic channel 410.

Each of the interaction regions 401 a, 401 b and 401 c is illuminated byan illumination source 420, 421 and 422 respectively. The illuminationsource 420 comprises an optical transmitter to generate an optical inputsignal and a waveguide to guide the optical input signal from theoptical transmitter to the interaction region 401 a. Likewise, theillumination source 421 comprises an optical transmitter to generate anoptical input signal and a waveguide to guide the optical input signalfrom the optical transmitter to the interaction region 401 b. Likewise,the illumination source 422 comprises an optical transmitter to generatean optical input signal and a waveguide to guide the optical inputsignal from the optical transmitter to the interaction region 401 c.

The optical sensor 400 comprises a first optical reservoir system 450 aand a second optical reservoir system 450 b. Each of the opticalinteractions regions 401 a, 401 b and 401 c may be coupled to one orboth of the optical reservoir systems 450 a and 450 b.

In FIG. 4 optical coupling structures 405 a, 405 b and 405 c areprovided to collect and forward transmitted parts of the respectiveinput signal of the first interaction region 401, the second interactionregion 401 b and the third interaction region 401 c respectively to bothof the optical reservoir systems 450 a and 450 b. It should again benoted that for ease of illustration not all waveguides that are arrangedaround the respective interaction regions are shown with a connection tothe optical reservoir systems 450 a and/or 450 b. According toembodiments, each of the waveguides may be connected to one of theoptical reservoir systems 450 a or 450 b or to other not shown opticalreservoir systems.

FIG. 5 shows a schematic illustration of a side view of an interactionregion 501 according to another embodiment of the invention. Such aninteraction region 501 may be combined with any of the optical sensors100, 200, 300 and 400 as described above. The optical interaction region501 comprises a first part 510 that is embedded in a chip and a secondpart 511 that is established in a free space manner by air or a liquid.An optical input signal 504 may be fed into the interaction region 501via an input waveguide 503 b that may receive the optical input signal504 from an optical transmitter 503 integrated into the chip. Theoptical input signal 504 interacts then with elements 502 thatcorrespond to an analyte and may e.g. be reflected back into one or moreof the waveguides of an optical coupling structure 505 which may thenforward the reflected parts to an optical reservoir system for furtherprocessing in the optical domain as described above.

According to the embodiment as illustrated in FIG. 5, the coupling fromthe waveguide 503 b to free space, both for illumination and detection,is done via butt coupling. According to other embodiments, this couplingmay be done by tapering down the waveguide in order to expand therespective mode into free space/the interaction region, or via gratingcouplers.

FIG. 6 shows a schematic illustration of a top view of an interactionregion 601 according to another embodiment of the invention. Theinteraction region 601 has a circular shape and may be combined with anyof the optical sensors 100, 200, 300 and 400 as described above. Theoptical interaction region 601 comprises a microfluidic channel 610comprising the interaction region 601. According to this embodiment, theinteraction region 601 is illuminated by two different illuminationsources 611, 612 which illuminate the interaction region 612 fromdifferent angles. The first illumination source 611 comprises an opticaltransmitter 611 a and a waveguide 611 b feeding an optical input signal604 a into the interaction region 601. The second illumination source612 comprises an optical transmitter 612 a and a waveguide 612 b feedingan optical input signal 604 b into the interaction region 601.

The optical input signals 604 a, 604 b may then interact with elements602 to be detected/analyzed and may e.g. be reflected back into one ormore of the waveguides of an optical coupling structure 605, which maythen forward the transmitted parts to an optical reservoir system forprocessing in the optical domain as described above. The illuminationsources 611, 612 may have the same or different emission spectra.

FIG. 7 illustrates method steps of a method for analyzing an analyte,e.g. a method for detecting elements, by an optical sensor, e.g. theoptical sensor 100 as described with reference to FIG. 1.

At a step 710, an illumination source, e.g. the illumination source 103of FIG. 1, illuminates an interaction region, e.g. the interactionregion 101 of FIG. 1.

At a step 720, an optical coupling structure, e.g. the optical couplingstructure 105 of FIG. 1, collects transmitted parts of the optical inputsignal from the interaction region 101.

At a step 730, the optical coupling structure 105 forwards thetransmitted parts of the optical input signal to an optical neuromorphicnetwork, e.g. the optical neuromorphic network 107 of FIG. 1.

At a step 740, the optical neuromorphic network 107 receives thetransmitted parts of the optical input signal from the optical couplingstructure 105.

At a step 750, the optical neuromorphic network 107 processes thetransmitted parts of the optical input signal in the optical domain.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method for analyzing an analyte by an opticalsensor, the method comprising: illuminating, by an illumination source,an interaction region comprising the analyte with an optical inputsignal; collecting, by an optical coupling structure, transmitted partsof the optical input signal from the interaction region; forwarding, bythe optical coupling structure, the transmitted parts of the opticalinput signal to an optical neuromorphic network; and receiving andprocessing the transmitted parts of the optical input signal in theoptical domain by the optical neuromorphic network.